A conventional torque wrench is shown in U.S. Pat. No. 7,703,357 and generally includes a ratchet drive portion with an insertion member, a moment arm, a torque-adjustable rod, an in-place-rotatable handle, and a torque setting pointer. A hollow sleeve is fixed at a distal end of the moment arm by a fixing element. An internal toothed portion is formed in a stepped hole of the hollow sleeve and positioned adjacent to one side of the in-place-rotatable handle. The internal toothed portion is, in the normal state, engaged with an external toothed portion of the in-place-rotatable handle by means of an elastic element located between the in-place-rotatable handle and the hollow sleeve. The elastic element has one end abutting the stepped hole of the hollow sleeve. The torque-adjustable rod of a torque adjusting mechanism is driven by the in-place-rotatable handle for adjusting the torque value when the in-place-rotatable handle is pushed in the direction of the hollow sleeve so as to disengage the internal and external toothed portions from each other, thereby achieving an expected adjustment. After the adjustment, the external force is released and the internal and external toothed portions are automatically restored in an engaged and locked position of the normal state by means of the self-resilience of the elastic element. The drawbacks of the torque wrench is that when the in-place-rotatable handle is rotated to drive the torque-adjustable rod, the torque setting pointer is moved so that the pointer points a certain value mark to show the pre-set value of the torque. However, the pointer and the marks are so small and the user has to check carefully the relative positions therebetween and this is difficult especially when the illumination condition is poor.
Another conventional torque wrench is disclosed in U.S. Pat. No. 7,685,889 and generally includes a body portion positioned between a handle portion and a driving portion. The driving portion has a driving head to drive the object by pre-set torque. The handle portion has a certain length for the users to hold and a space is provided in the body portion for installing an electronic mechanism inside the body portion. The electronic mechanism has a volume for installing at least two electronic units therein and the electronic units are stacked to reduce the space required so that more electronic units can be installed to have multiple functions. Nevertheless, the electronic units need batteries to function and once the power from the batteries is gone, the display function fails.
The present invention intends to provide a torque wrench having electronic and mechanical display units.